how to redirect to a form from a page in living application

I have created forms and pages by following bonitasoft getting started tutorial.and I made it to a living application.

How to redirect to a form from a page?

I need to go to the process instantiation form(create a new request). I tried several times and failed.

Also I would like to know what exactly "processDef" variable does.Is that referring to a form or a page?Is that variable helping me with the redirection to form/page.